Examples

announcement1.jpg
Store sign announcement.jpg
book-release-announcement-09.jpg
Characteristics (must have)
-specific topic
-place
-date
-time
-address
-contact information
-information about what there is to offer-why they should go

Criteria (how to make it good)
-be concise-to the point
-catch the reader's attention-font, size, color, shape
-pictures/visuals
-make the main point stand out
-persuasive almost
-not too much detail